Lung Cancer Diagnosis

Doctors use a wide range of diagnostic procedures and tests to diagnose lung cancer. These include but are not limited to:

• A complete medical history (to check for risk factors and symptoms) and a physical examination which may reveal the presence of symptoms or signs that give an indication of lung cancer. In addition to asking about symptoms and risk factors for cancer development, doctors may detect signs of breathing difficulties, airway obstruction, or infections in the lungs.


• Blood tests - Although routine blood tests cannot diagnose lung cancer alone, they may reveal abnormalities in the body that may be associated to cancer.


• The chest x-ray is the most common first diagnostic step when any new symptoms of lung cancer are present. The chest x-ray procedure often involves a view from the back to the front of the chest as well as a view from the side. Like any x-ray procedure, chest x-rays expose the patient briefly to a minimum amount of radiation. Chest x-rays may reveal suspicious areas in the lungs but are unable to determine if these areas are cancerous.


• Bronchoscopy - the examination of the bronchi (the main airways of the lungs) using a rigid or a flexible tube (bronchoscope). Bronchoscopy helps to evaluate and diagnose lung problems, assess blockages, obtain samples of tissue and/or fluid, and/or to help remove a foreign body. The procedure can be uncomfortable and require sedation or anesthesia. After this procedure patients may cough up dark-brown blood for one to two days. More serious complications may arise as well.


• Sputum cytology - The diagnosis of lung cancer always requires confirmation of malignant cells by a pathologist, even when symptoms and x-ray studies are suspicious for lung cancer. The simplest method to establish the diagnosis is the examination of sputum (a secretion that is produced in the lungs and the bronchi) under a microscope. If a tumor is centrally located and has invaded the airways, this procedure, known as a sputum cytology examination, may allow tumor cells to be visible for diagnosis. This is the most risk-free and inexpensive tissue diagnostic procedure, but its value is limited since tumor cells will not always be present in sputum even if a cancer is present. Unfortunately, noncancerous cells may occasionally undergo changes in reaction to inflammation or injury that makes them look like cancer cells.


• Positron emission tomography (PET) - a specialized imaging technique that uses short-lived radioactive substances to produce three-dimensional colored images of those substances functioning within the body. Combining glucose (a common energy source in the body) with a radioactive substance will show where glucose is being used in a growing tumor. Tissues that use the glucose more than normal tissues (such as tumors) can be detected by a scanning machine. PET scans can be used to find small tumors or to check if treatment for a known tumor is working.